Issue when using tables/class with generics?

How are you using the lua-language-server?

Visual Studio Code Extension (sumneko.lua)

Which OS are you using?

Windows

What is the issue affecting?

Type Checking

Expected Behaviour

In the following code:

---@class TestClass
---@field test string
---@field test2 string

---@param test TestClass
local function test_function(test)
	for k, v in pairs(test) do end

	---@type {test: string, test2: string}
	local test_table

	for k, v in pairs(test_table) do end

	---@type {test: string, test2: string}
	local test_table2 = {
		test = "test",
		test2 = "test2",
	}

	for k, v in pairs(test_table2) do end
end

I would hope that the inferred type of k and v would work the same in each instance where k is inferred to be a string and v is inferred to be a string.

Actual Behaviour

In the following code:

---@class TestClass
---@field test string
---@field test2 string

---@param test TestClass
local function test_function(test)
	for k, v in pairs(test) do end

	---@type {test: string, test2: string}
	local test_table

	for k, v in pairs(test_table) do end

	---@type {test: string, test2: string}
	local test_table2 = {
		test = "test",
		test2 = "test2",
	}

	for k, v in pairs(test_table2) do end
end

the k and in line: for k, v in pairs(test) do end and the k in line for k, v in pairs(test_table) do end get the error can not infer type and are typed as unknown.

I assume there is some issue here with generics as the pairs definition uses them heavily

---@generic T: table, K, V
---@param t T
---@return fun(table: table<K, V>, index?: K):K, V
---@return T

but this is only a guess.

Reproduction steps

1. Copy this code:

---@class TestClass
---@field test string
---@field test2 string

---@param test TestClass
local function test_function(test)
	for k, v in pairs(test) do end

	---@type {test: string, test2: string}
	local test_table

	for k, v in pairs(test_table) do end

	---@type {test: string, test2: string}
	local test_table2 = {
		test = "test",
		test2 = "test2",
	}

	for k, v in pairs(test_table2) do end
end

2. See errors

Additional Notes

No response

Log File

No response

まず、提供されたスニペットを Visual Studio Code 拡張機能で再現し、次に pairs の定義とそのジェネリックな戻り値の型を調べます。TestClass、未初期化テーブル、初期化済みテーブルのケースで、can not infer type エラーなしに k と v が string として推論されれば、修正は完了です。